Spam mails which bother us are dramatically been increasing. Filtering is one of the effective Anti-spam method. But if it based on analyzing the body of mail, some legitimate mails are not deliver to destination. In this thesis, we focused on Received field in the mail header, and analyze the delivery path. This paper presents delivery delay time at a legitimate mail server tends to be a constant. Furthermore, spam mails delivery delay time are dispersedly. Additionally, we described some spam mais uses wrong summer time, and have special count of Received fields.